PROJECT ABSTRACT This novel, exploratory research applies a social network approach to the conceptualization and measurement of pregnant women's family contexts. We will examine how the overarching structure of mothers' self-defined family networks, and the quality of interactions within them, shape maternal health through two pathways: health behaviors and psychosocial well-being. Prior research on family and maternal health focuses primarily on parents' relationship status or ?family structure,? dyadic relationship quality between parents or parent and child, or global questions about family support in relation to health. Our research innovates by collecting ego- network data from pregnant women about their families to capture the structural and interactive properties of families. Our two specific aims are to (1) collect family network data and health and birth outcome data for 400 pregnant women, and (2) test a conceptual model linking family network characteristics to maternal health outcomes through behavioral and psychosocial pathways. To accomplish these aims, we will develop a quota sample of 400 women (n=400) from the electronic medical records of one health care system that is predominant in two counties of NC. The sample will be diverse in race/ethnicity, social class, and urban, suburban, or rural residence. Women in their fourth or fifth month of pregnancy who voluntarily consent to the study will participate in a 45-minute interview that includes a structured set of questions to measure their family networks and the support, conflict, and control moving across ties. We will also include less-structured questions to understand if we are overlooking family dynamics that matter for health. The network data we collect on tablets using EgoWeb 2.0 will be analyzed quantitatively, to examine several dimensions of family networks and investigate how variance in those relates to maternal and child health outcomes. We will also assess whether any of these associations are explained by women's health behaviors or psychosocial well- being. We will transcribe the less-structured parts of the interview into qualitative data for analyses to uncover which aspects of family context we might be missing or misunderstanding. Findings from this study will spark new research and motivate policies and programs that are attentive to a richer set of family dynamics and their bearing on health. Moreover, our use of EMRs for sampling pregnant women and collecting health and social data will model new, groundbreaking alternatives for population health research.